The present invention relates to apparatus for forming fresh insulation, hereinafter sometimes referred to as an "insulation splice" about a relatively short section of an uninsulated conductor of a high voltage cable.
Such insulation forming devices are presently in use for repairing damaged cable insulation or for forming new insulation about a cable splice, for example. For high voltage cable such insulation may be of a thickness of as much as one-half inch or more. The insulation splice must be homogenous within itself, that is, it must be free of discontinuities and it must further be homogeneously bonded to existing cable insulation to prevent the formation of electrical interfaces which may lead to corona discharges and a premature failure of the insulation splice.
In the prior art it was initially common to form such insulation splices manually. The task required skillful operators, was time-consuming and therefore expensive, and further frequently yielded unreliable insulation splices. This inventor has previously invented apparatus for reliably and reproducibly forming high quality, high voltage cable insulation splices. One such device is described, for example, in co-pending patent application Ser. No. 344,103, filed Feb. 20, 1973, now U.S. Pat. No. 3,880,557, entitled MOLDING METHOD FOR SPLICING ELECTRICAL CABLE. The device described in that co-pending patent application broadly comprises a pair of mold forms which define therebetween a cavity within which the insulation splice is formed and cured. Hingeably interconnected pressure platens are provided for heating the mold halves and pressing them together during forming and curing of the insulation. This device has found great commercial acceptance and is ideally suited for many industrial applications.
The need for the increasingly larger pressures, particularly when forming polyethylene insulation splices, together with requirements of making splices in areas having limited accessibility, such as municipal high voltage cable racks has rendered the device disclosed in the referenced patent application at times difficult to use.